The present invention relates to a system for monitoring leaks in conduits and containers. In particular, the invention relates to the electronic monitoring of leaks in gas venting systems, fluid piping systems, heat exchangers, fluid storage or processing tanks or other conduits and containers due to corrosion penetration or joint separation.
As homes and buildings become more air tight, there has become a need to insure that the exhaust vents of natural gas, propane, and oil fired heating appliances, hot water heaters, and boilers have not separated or corroded to the point that harmful flue gases are allowed to escape inside of structures rather than being exhausted outside of the structure. The escape of flue gas can expose the occupants of the structure to carbon monoxide and other hazardous gases found in flue gases. With less fresh air entering the structure, there is a greater risk of harmful gases concentrating inside of the structure.
In order for the appliance to fail safe in the case of vent deterioration, there must be a device that can detect the leak and interrupt the ability of the appliance to fire or run while the unsafe condition exists. There is government pressure being brought upon appliance manufacturers and the heating industry to require that control systems be incorporated into appliances as part of the future certification process. Many deaths have been attributed to conduit deterioration or joint separations.
When the conduit or container is being used to conduct or contain acidic, caustic, radioactive or hazardous liquids, it is also important to have the means to detect a leak and sound an alarm and/or prevent the pump from continuing to deliver the liquid into a deteriorated pipe system or a system in which the joints have separated. The continued flow of liquid though a deteriorated or separated piping system can cause bodily harm and/or physical property damage.
Previous control systems for power assisted venting products have relied on the ability of the control system to detect changes in the negative air pressure of the interior of a vent system. This is sometimes inaccurate due to the fact that there are endless potential configurations with different lengths and numbers of bends and elbows which will significantly influence the negative air pressure within a vent system. When the configuration variables are combined with pressure variables caused by changing barometric pressures, changing wind directions and wind speeds, pressure sensors can detect many false or confusing readings causing nuisance shut downs.
There is a need for a reliable, inexpensive, and simple system to detect conduit failures which is not prone to false readings leading to wasteful equipment shut downs.
The present invention provides for multiple layers of electrically conductive and electrically insulating materials which would be isolated from each other as long as there is no deterioration or penetration of the wall of the conduit or container. Should there be a corrosion penetration of the wall of the conduit or container caused by flue gas condensate or corrosive fluid, the condensate or liquid would act as a conductor to allow increased electrical current to pass from one electrically conductive layer to another electrically conductive layer. The increased conductance will change the electrical resistance of the overall system, change the electrical capacitance of the system, or result in a direct circuit if the voltage is high enough and the fluid has a low enough resistance to allow sufficient current to flow between the two conductive layers. The change in electrical resistance or capacitance can be measured and a signal can be conveyed to a control device to stop operation of the equipment and/or sound an alarm.
Changes in electrical capacitance and resistance of the system are evident in the case of full and partial corrosion penetration of the insulating layer between the electrically conductive layers. Where condensate has only partially penetrated into the insulative layer, small changes in resistance and conductance will result. A higher level of sensitivity will be required to detect such changes but will nonetheless allow the system to detect an impending fault. In contrast, when full corrosion penetration has occurred or when a pipe joint has completely separated, much larger changes in resistance and conductance will result necessitating less sensitive detection.
Alternatively, the completed circuit can blow an electrical fuse and interrupt the supply of electrical current to the equipment and/or sound an alarm.
Presently most venting and pipe systems use a single material such as metal or plastic to form pipe lengths and joint elbows. Using an electrical current to monitor the integrity of such a system is not possible because there is not a second conductive layer to create electrical capacitance which can be used for detection purposes in the event that there is a corrosion penetration of the walls of the pipe. In order to create electrical capacitance, there must be two or more layers of electrically conductive plates or coating layers which are separated by an insulator layer.
In one aspect, the invention provides a leak detection system comprising a leak detection system comprising:
a conduit for conducting a fluid or gas, said conduit being defined along its length by first and second layers of an electrically conductive material, said first and second layers being electrically insulated from each other;
means for electrically insulating said conduit from input and output connection members;
control means for detecting a leak in said conduit, said control means including output means for introducing an electric charge to said first or second conductive layers of said conduit, detector means for detecting changes in said electric charge in said first and second conductive layers, and response means for triggering a predetermined response when a sufficient change in said electric charge is detected.
In another aspect, the invention provides a leak detection system comprising a leak detection system comprising:
a conduit for conducting a fluid or gas, said conduit including means for carrying an electric charge along the entire length of said conduit;
means for electrically isolating said conduit from input and output connection members;
means for connecting the ends of said conduit to a power source for actuating said fluid or gas flow, wherein said conduit forms part of a circuit with said power source, and wherein a separation of one or more of said conduit sections will interrupt the flow of current in said circuit and cause said power source to deactivate said fluid or gas flow. dr
FIG. 1 is a side view of a leak detection system in accordance with the present invention;
FIG. 2 is a plan view of a conduit section for the leak detection system of FIG. 1;
FIG. 3 is a sectional view of the conduit section of FIG. 2, taken along lines 3xe2x80x943;
FIG. 4 is an enlarged view of the connection between the appliance adapter and conduit section for the leak detection system of FIG. 1;
FIG. 5 is an enlarged view of an alternate connection between adjacent conduit sections for the leak detection system of FIG. 1;
FIG. 6 is a block diagram of a leak detection system in accordance with the present invention;
FIG. 7 is a block diagram of an alternate leak detection system in accordance with the present invention;
FIG. 8 is a circuit diagram of the control device for the leak detection system of FIG. 1;
FIG. 9 is a plan view of an alternate conduit section for a leak detection system in accordance with the present invention;
FIG. 10 is a sectional view of the conduit section of FIG. 9 taken along lines 10xe2x80x9410;
FIG. 11 is a longitudinal sectional view of a conduit section incorporating an alternate leak detection system in accordance with the present invention;
FIG. 12 is a side view of a building with a vertical conduit incorporating an alternate leak detection system in accordance with the present invention;
FIG. 13 is a sectional view of two conduit sections for an alternate leak detection system in accordance with the present invention;
FIG. 14 is an end view of one of the conduit sections of FIG. 13;
FIG. 15 is a partial plan view of two connected conduit sections for an alternate leak detection system in accordance with the present invention; and
FIG. 16 is a partial sectional view of two connected conduit sections for an alternate leak detection system in accordance with the present invention.